Metamaterials can exhibit such properties as negative refraction and cloaking from microwaves. See Pendry et al., 2006, Science 312, 1780. A low-frequency and/or DC metamaterials can be made out of diamagnetic substances, for example, a superconductor, allowing for engineering of magnetic cloaks, which can shield the magnetic field in their interior without substantially affecting the field on the outside. See, e.g., Wood et al., 2007, J. Phys.: Condens. Mater. 19, 076208, Magnus et al., 2008, Nature Mater. 7, 295. A DC metamaterial made of superconducting Pb flakes (or plates) that operates in the presence of liquid helium temperature (T=4.2 K), since the superconducting temperature (Tc) is approximately 7 K, has been disclosed (see Magnus et al.). One of the main obstacles for a broad practical use of the superconductor-based metamaterials is the low operation temperature and cryogenic liquids that may be required for such operation, such as helium (T=4.2 K) or nitrogen (T=77 K), in the case of a high-Tc superconductor).
A DC metamaterial structure capable of operating at room temperature is beneficial.